Tungsten-hafnium alloy casting



United States Patent 3,116,145 TUNGSTEN-HAFNIUM ALLOY CASTING M'arion Sernchyshen, Dearborn, Mich, assignor to American h fetal Uimax, Inn, New York, N.Y., a corporation of New York No Drawing. Filed Apr. 30, 1962, Ser. N 191,305 9 Claims. (Cl. 75-176) The present invention relates to cast tungsten base alloys containing hafnium and which are characterized by the fact that they are capable of being worked at elevated temperatures and have unusually high strength and hardness at temperatures above 2000 F. This application is a continuation-in-part of applicants copending application, Serial No. 41,766, filed July 11, 1960.

The alloys of the present invention are castings containing from 02% to 5% hafnium, up to .50% carbon. The balance consists essentially of tungsten except that small quantities of zirconium, tantalum, columbium or molybdenum may be present as optional ingredients. Thus, one or more of the elements of zirconium, tantalum and columbium may be present in amounts not exceeding a total of about 1% and molybdenum may be present in an amount not exceeding about Oxygen, even in the smallest amounts, is deleterious and hence must be less than 005% and preferably less than 001%.

Highly useful alloys within the scope of the present invention include alloys containing .01% to .10% carbon. However, when carbon is present in amounts in the order of .01% or more, the hafnium content should not exceed about 1%. Larger quantities of hafnium, within the limits stated above, may be present in carbon free alloys or alloys containing less than .01% carbon.

The alloys of the present invention may be prepared by arc-melting in vacuum, preferably using a furnace of the type disclosed in the United States Patent 2,656,743. A a

preferred method of deoxidizing the melt is by adding carbon to the charge to react with any oxygen present in raw materials and in quantities which will leave the desired excess in the final casting. The absolute pressure during the melting operation is preferably maintained below 50 microns of mercury.

The following are specific examples of alloys coming within the scope of the invention:

The alloys of the present invention may be forged or Worked at temperatures in the neighborhood of 3600 F. to 4000 F.

All proportions given are proportions by weight.

What is claimed is:

1. A cast alloy containing from .O2% to 5% hafnium, up to carbon, less than .005 oxygen, not more than 1% of metal from the group consisting of zirconium, tantalum and colurnbium, not more than 10% molybdenum and the balance consisting essentially of tungsten.

2. A cast alloy containing from 02% to 1% hafnium, up to 50% carbon, less than 005% oxygen, not more than 1% of metal from the group consisting of zirconium, tantalum and columbium, not more than 10% molybdenum and the balance consisting essentially of tungsten.

3. A cast alloy containing from 02% to 1% hafnium, up to .10% carbon, less than .005 oxygen, not more than 1% of metal from the group consisting of zirconium, tantalum and eolurnbium, not more than 10% molybclenum and the balance consisting essentially of tungsten.

4. A cast alloy containing from 02% to 5% hafnium, up to 50% carbon, less than 005% oxygen, not more than 10% molybdenum and the balance consisting essentially of tungsten.

5. A cast alloy containing from 02% to 1% hafnium, up to 50% carbon, less than 005% oxygen, not more than 10% molybdenum and the balance consisting essentially of tungsten.

6. A cast alloy containing from 02% to 1% hafnium, up to .10% carbon, less than 005% oxygen, not more than 10% molybdenum and the balance consisting essentially of tungsten.

7. A cast alloy containing from 02% to 5% hafnium, up to .50% carbon, less than 005% oxygen, and the balance consisting essentially of tungsten.

8. A cast alloy containing from 02% to 1% hafnium, up to .50% carbon, less than 005% oxygen, and the balance consisting essentially of tungsten.

9. A cast alloy containing from 02% to 1% hafnium, up to .10% carbon, less than 005% oxygen, and the balance consisting essentially of tungsten.

References Cited in the file of this patent UNITED STATES PATENTS 2,234,969 Hensel et a1 Mar. 18, 1941 2,580,273 Bens et a1. Dec. 25, 1951 2,678,268 Ham et al May 11, 1954 2,678,269 Ham et a1 May 11, 1954 2,678,270 Ham et al May 11, 1954 2,678,271 Ham et al May 11, 1954 2,678,272 Ham et a1 May 11, 1954 2,798,808 Iredell et al July 9, 1957 2,947,624 Semchyshen Aug. 2, 1960 2,977,225 Wlodek et a1 Mar. 28, 1961 FOREIGN PATENTS 216,840 Great Britain June 29, 1925 1,233,810 France May 9, 1960 

1. A CAST ALLOY CONTAINING FROM .02% TO 5% HAFNIUM, UP TO .50% CARBON, LESS THAN .005% OXYGEN, NOT MORE THAN 1% OF METAL FROM THE GROUP CONSISTING OF ZIRCONIUM, TANTALUM AND COLUMBIUM, NOT MORE THAN 10% MOLYBDENUM AND THE BALANCE CONSISTING ESSENTIALLY OF TUNGSTEN. 